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Capybaras (Hydrochoerus spp.) Fact Sheet: Behavior & Ecology

Activity Cycle

  • Rest close together at water's edge in morning
  • Rest in water or mud during the heat of the day
  • Most grazing in late afternoon and evening; graze in short sessions at night
  • After disturbances from humans, more nocturnal and shy
  • Group size fluctuates with wet/dry seasons

Home Range

Territory Size

  • Territories remain very stable for several years
  • Along rivers, groups space themselves from 100 to 500 m (.06 to .3 mi.) apart
  • Groups may occupy a home range from 2 to 200 hectares (4.9 to 494 acres)
  • Average group uses 5 to 20 hectares (12.4 to 49.4 acres)
  • In one study, each group used a home range averaging about 79 hectares and defended a territory of 9 hectares
  • Density of capybara within their territories quite high compared to other tropical herbivores of similar size
    • Biomass of capybara 10 times greater than similar sized grazing Bohr's reedbucks' biomass
    • Density of capybara populations reflects high primary productivity of savanna habitats in Llanos of Venezuela

Social Groups

General

  • Social animals living in groups
    • Dry season: up to 100 individual at water sources
    • Wet season: group size up to 40 individuals
  • Bonds between animals maintained by touching, grooming, scent marking, vocalizations
  • High levels of sociality possibly a response to risk of predation and resource availability
    • Capybara similar in this trait to South American desert and rock cavies and maras

Hierarchy

  • Herds with dominant and subordinate males plus females and young
  • Typical make-up of breeding groups: one male and 4-14 females
  • Dominance positions very stable, lasting for years
    • Dominant male may claim access to best water holes, parasite-eating birds, and females in estrus
    • Largest males are usually dominant individuals
    • Size not a factor in status among subordinate males
    • Subordinate males tend to occupy positions on edges of resting groups, away from dominant male
  • No bachelor groups
    • Males not in groups have little protection from predators
    • Outside the group, no chance for reproduction

Territorial Behavior

Groups defend territories

  • Exception to this rule: quick unchallenged passage by neighboring capybara to reach distant territory
  • Capybara bark at intruders; then if necessary, jump in river or run away

Scent-mark using anal glands

  • Performed by both sexes
  • May play a role in defining territories

Aggression

  • Male aggression more frequent with increasing numbers of males in group
  • Harassment and chasing = main form of male/male aggression
    • Subordinate males rarely retaliate
    • Retaliation involves facing opponent, both animals rushing towards each other, rearing on hind legs, grappling, loser fleeing
    • Subordinate males often suffer serious bites to rump as they flee
    • Most commonly, dominant male walks, nudges, or "escorts" subordinate male to edge of group
  • Grooming lessens tension between individuals and removes parasites

Social Interactions

Play

  • Young in groups play in water, imitate males
  • Like other cavy-like social rodents, individuals chase each other, play-wrestle, gallop

Communication

Visual Signals

  • Greatly enlarged scent glands on top of snout in male signals status and may attract females
    • Size of male's morrillo is a sign of rank

Vocalization

  • Infants and young constantly emit a guttural purr, perhaps to stay in touch with group; losers in aggressive matches also make this sound in appeasement
  • Low clicking sounds of contentment
  • Sharp prolonged whistles, squeals, short grunts
  • Alarm bark or cough
  • Most warning calls come from subordinate males in a group; companions react by standing alert or plunging into nearest water
  • Females emit a whistle when in estrus
  • Males tooth-chatter as sign of aggression
  • Many other closely related species also highly vocal, especially guinea pigs and cavies
  • Capybara audio provided by BBC

Olfaction/Scent Marking

  • Amount of scent-marking correlates with dominance rank 
  • Both sexes scent mark with anal gland; females less frequently
  • Group members may recognize each other by their unique mix of scent chemicals

Locomotion

  • Excellent swimmer; good diver, can stay underwater for up to 5 minutes
  • Move from place to place in short bursts of travel not more than 200 m. (.12 mi.) with long rests between
  • Walks, grazing, in typical day about 700 m (.43 mi)
  • Star-shaped footprints
  • Rather sedentary habits allow ranchers to manage capybara without fences
  • Several juveniles may ride on female's back, as she swims

Interspecies Interactions

  • Predators: puma, jaguar, wild dogs, humans
  • Juveniles preyed upon by foxes, ocelots, cayman, raptors, occasional possums (attacking infants), anaconda
  • When attacked by wild dogs, capybara group forms defensive huddle with young in center, adults facing outwards
  • Co-exist with domestic cattle
  • At least nine species of birds increase their feeding rate by associating with capybara
    • Especially jacana, scarlet ibis, sharp-tailed Ibis, white Ibis, buff-necked ibis, swifts
    • Egrets hunt from moving and stationary capybara's backs
    • Swifts hunt low overhead or from capybara's head
    • Researcher observed capybara soliciting tick-eating (Amblyomma spp.) by yellow-headed caracara
  • Five bird species associated with capybara in order to find food. (Tomazzoni et al 2005)
    • Southern caracara, rufous hornero, cattle tyrant, yellow-headed caracara, shiny cowbird
    • Strategies of the birds included using the capybara as a perch, walking with the capybara to catch flushed prey, foraging in capybara skin

Capybara (Hydrochoerus hydrochaeris)

Capybara and baby

Image credit: © San Diego Zoo Global. All rights reserved.

Page Citations

Lord-Rexford (1994)
Herrera & Macdonald (1989, 1993)
Macdonald (1981a, b)
Nowak (1999)
Ojasti (1991)
Rowe and Honeycutt (2002)
Tomazzoni et al (2005)

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